If you want health care you have to be in your home province for between 6 months and 200 days. Check your plan as each one is a bit different.
Most travel insurance demands you have a valid Canadian health plan in effect.
Should you use an address out of Canada you will not qualify for certain benefits, like OAS supplement or health care.
Should you be caught in the USA for over 182 days you can be deported and they will not allow you back into the country for some time.
Of course they will also probably ask you to file a tax return.
Most car insurance requires the vehicle be in Canada for at least 6 months out of the year. The DMV requires a physical address on document, a PO box is not good enough.